The purposes of this study are a) to assess the significance of psychiatric disorders in cocaine abusers, b) to adapt and evaluate existing diagnostic methods for use with cocaine abusers, and c) to assess other clinical correlates of cocaine abuse. To serve these purposes we propose to evaluate psychiatric diagnosis, addictive behaviors, family psychiatric history, personality characteristics, psychological symptoms, legal history, social functioning, medical history, and occupational/financial support in 450 cocaine abusers in three subsamples: 150 subjects entering outpatient treatment, 150 subjects entering inpatient treatment, and 150 untreated cocaine abusers in the community. Rates of psychiatric disorders and patterns of other clinical characteristics will be compared across the different cocaine abusing samples and between cocaine abusers and comparison groups of opiate addicts, depressives, normals, and community samples. To assess the utility of diagnostic methods several methodological studies will be performed on subsamples. Short range retesting (20-28 days following admission) will be performed on the inpatient sample to evaluate the effect of recency of cocaine abuse on diagnosis. Conjoint interviewing will be performed to assess interrater reliability. Evaluation of significant other informants will be performed to assess concurrent validity of information obtained from cocaine abusers. A one year follow-up reassessment will be performed to assess diagnostic stability, long term test-retest reliability and prognostic significance of psychiatric diagnosis. Detailed assessment of family psychiatric diagnosis in first and second degree relatives will be performed with cocaine abusers to provide pilot data for future studies of family/genetic factors in cocaine abuse.